This invention relates to the direct topical medication of fishes, amphibians, reptiles, and aquatic macroinvertebrates. More specifically, this invention relates to topical medicants for individual such aquatic and semi-aquatic animals applied in a site-specific manner for the localized treatment of skin wounds, lesions and diseases.
In the animal health care field, there have been many advances in the veterinary sciences for the disease treatment of mammals as a result of the important roles of livestock and pets in our society. Historically, the same emphasis has not been placed on the care and treatment of diseased cold-blooded life forms. As the economic impact of aquaculture practices such as fish farming grows, as well as sophistication of commercial, public and hobby aquarium and terrarium maintenance, greater attention is being given to the medical needs of fishes, amphibians, reptiles, and aquatic macroinvertebrates.
Traditional methods for treating fishes involve administering a therapeutic agent orally with feed, parenterally by injection, or by dispersing in a water bath or dip. By far the most frequently used treatment method involves medicating the water in which the fish lives. U.S. Pat. No. 4,110,467 to Sano et al. and U.S. Pat. No. 4,852,519 to Karlsen are examples of the state of the art techniques for medicating water in order to treat fishes.
The well-known problems of “fin and tail rot”, “mouth fungus”, cataracts of the eyes, as well as wounds and lesions, are treated with therapeutic topical baths of indeterminate length or short-term dips. In all of these examples, there are either no known treatments, or treatments which have not always been effective due to the inability to get sufficient therapeutants to the site of active disease, or due to loss of the therapeutants in the bath as a result of decomposition or adsorption onto gravel, rocks and other decorations and implements in the environment, as well as removal by filtration.
Mass treatments in the form of baths and dips suffer a variety of drawbacks. Such technique is likely to waste therapeutants, to expose non-diseased animals to the treatment, and to potentially destroy non-target microbes such as the nitrifying bacteria in aquarium or pond biological filtration. The inability to accurately calculate the exact volume of water being treated in an aquarium or pond typically leads to undesirable under-dosing or over-dosing of the treatment. In addition, there is the danger of creating resistant strains of disease-causing organisms by exposing other than the target organisms to otherwise effective therapeutants. And, although useful against the target organisms, therapeutants in a water bath or dip may be toxic to the animals being treated.
Apart from limited use of the topical bath/dip treatments for diseases of fishes, reptiles and amphibians, treatments for aquatic macroinvertebrates are less well known. Macroinvertebrates include crustaceans, mollusks, corals, echinoderms such as sea cucumbers and sea stars. For example, a major problem in the husbandry of brittle sea stars (i.e., starfish) is the loss of the animal's arms during shipping or handling. Such an injury can easily result in the loss of internal fluids and the invasion of disease-causing microbes. Similarly, bacterial infections of stony corals cause widening spots or bands to appear on the coral heads or extensions. Topical treatment by bath medication for such wounds and diseases has not proven efficacious.
As used in this disclosure, the term “topical” refers to any substance, compound or mixture that is applied directly to the integument (e.g., skin) of invertebrate and vertebrate animals. Such application may consist of direct deposition on the integument by means of swabbing, spraying, bathing, plastering, or rubbing.
For various reasons, each application method has identifiable drawbacks. For instance, in fishes, amphibians and aquatic macroinvertebrates, the application of topical treatments is most often in the form of a bath where the animal is immersed in the medicated water for periods of a few seconds to a week or more. The obvious problems associated with baths are: (1) the difficulty of accurately calculating dosages in oddly shaped bodies of water; (2) the reaction of the dissolved or dispersed medication with other substances in the water; (3) the removal of the medication by filtration or by simple adsorption on container walls or substrates; (4) the inability to readily determine the efficacy of the treatment; (5) the exposure of otherwise healthy animals to a treatment that may only be needed for a single specimen; (6) the inability to easily determine the concentrations of therapeutants in baths and dips; and (7) the exposure of a mixed species population to a treatment that may be toxic, or otherwise detrimental, to some of the species in the culture water.
Topical medicants applied as ointments and salves have been primarily made for veterinary use. In nearly every instance these have been oil or petroleum jelly based products, which do not adhere well to the wetted skin of fishes. In those exceptional instances where these products are water based, the viscosity is such that they do not remain on the area to which they are applied, and they lack properties that allow them to adhere to the area of application without quickly washing off into the surrounding water.
Plastering, daubing, rubbing, swabbing and spraying are the typical application methods of topical treatments for semi-aquatic animals. For instance, antimicrobial ointments are routinely used to treat lesions and wounds on herpatiles (i.e., reptiles and amphibians). Such ointments are typically swabbed using sterile cotton-tipped applicators, daubed directly from the container, plastered using plastic, metal or wooden applicators, or rubbed onto the site needing treatment with a properly gloved hand or finger. In such applications, the wounds or lesions are usually debrided to remove dead and decaying tissue and contaminates. Among the drawbacks to such applications are the necessity to capture and restrain the animal being treated, the possibility of exacerbating the severity of the lesions or wounds during capture and restraint, and the necessity of direct contact with an application instrument to properly apply the ointment.
Sprays suffer from the problem of dispersing the medication in a liquid form that will easily pass through an applicator orifice without clogging. In addition, sprays will typically cause the medication to be applied to a wider than necessary area of the animal's integument or immediate environment, thus wasting the medication. Treatments that are of a low enough viscosity to pass easily through a spray nozzle will typically run off vertical surfaces and may not provide sufficient coverage of the area to be treated. Another concern is that the sound, odor or temperature of sprays may startle or frighten the animal being treated.
The application of powders through dusters or direct application with a utensil suffers essentially the same drawbacks of liquid sprays and of ointments. With powders, there are the additional concerns of the powder not readily adhering to the lesion or wound being treated and being quickly shed or dispersed into the treated animals' environments. In the case of aquatic and semi-aquatic animals, powdered medications are practically useless for the foregoing reasons. For animals such as lizards, snakes, tortoises and toads, the animal crawling through water in its environment makes the use of powdered medications difficult and ineffective in most circumstances.
Accordingly, there remains a need in the animal health care field for therapeutic formulations and reliable methods of applying such formulations to fishes, amphibians, reptiles, and aquatic macroinvertebrates. The primary objective of this invention is to meet this need.